Cosmic Scale
Andromeda Galaxy
Spiral galaxy · 2.5 million light-years
How big is Andromeda Galaxy?
Andromeda Galaxy is about 152,000 light-years across.
See Andromeda Galaxy in 3D, at true scale
Andromeda is the nearest large galaxy and the most distant thing most people can see without a telescope. Its light left 2.5 million years ago, when our ancestors were first making stone tools.
At a glance
| Diameter | 152,000 light-years |
|---|---|
| Mass | 2.98 × 10⁴² kg |
| Diameter compared with Earth | 1.1 × 10¹⁴ × Earth |
| Distance | 2.5 million light-years |
| Stars | About 1 trillion |
| Also known as | M31 |
Good to know
- It is approaching us at 110 km/s; the two galaxies will merge into one huge elliptical.
- The Persian astronomer al-Sufi described it as a 'small cloud' in AD 964.
- In 1923 Edwin Hubble showed it lies far outside the Milky Way, proving that other galaxies exist.
- Next smaller: Milky Way · 100,000 light-years
- Next larger: Condor Galaxy · 522,000 light-years